Electromagnetic wave shield film, printed wiring board using same, and rolled copper foil

Abstract

An electromagnetic wave shield film in which peeling off between a metal thin film and an adhesive layer is prevented and a printed wiring board employing the electromagnetic wave shield are provided. An electromagnetic wave shield film is formed by laminating at least a metal thin film and an adhesive layer in order, and the water vapor permeability of the electromagnetic wave shield film according to JISK7129 is 0.5 g/m 2 per 24 hours or higher at a temperature of 80 degrees centigrade, a moisture of 95% RH, and a pressure difference of 1 atm.

We claim: 
     
       1. A method for manufacturing an electromagnetic wave shield film comprising at least a metal thin film and an adhesive layer, the metal thin film and the adhesive later being laminated in order, wherein, water vapor permeability according to JISK7129 is 0.5 g/m 2  or higher per 24 hours at a temperature of 80 degrees centigrade, a moisture of 95% RH, and a differential pressure of 1 atm, the method comprising:
 a step of preparing a carrier copper foil having a roughened surface with a release layer formed thereon, the roughened surface having a roughness Ra of 4 μm to 10 μm; 
 a step of forming an electro-deposited copper foil on the release layer, the electro-deposited copper foil having thick parts and thin parts attributable to the roughened surface of the carrier copper foil; 
 a step of making the metal thin film by peeling the electro-deposited copper foil from the release layer such that pin holes are formed in sufficient area density to yield vapor permeability of 0.5 g/m 2  or higher per 24 hours as the thin parts of the electro-deposited copper foil break; and then 
 a step of laminating the adhesive layer on the metal thin film; 
 wherein the area density of the pin holes is 10 to 1000 holes/cm 2 ; and 
 wherein the pin holes have diameters of 0.1 to 100 μm. 
 
     
     
       2. The method for manufacturing an electromagnetic wave shield film according to  claim 1 , wherein the electro-deposited copper foil has a thickness of 0.5 to 12 μm.